Spherical surface generating device



Aug. 7, 1945.

Filed Nov. 14, 1942 8 Sheets-Sheet 1 L3 INVENTOR.

A 7, 1945- A.. J. HOLMAN SPHERICAL SURFACE GENERATING DEVICE Filed Nov. 14, 1942 8 Sheets-Sheet 2 INVENTOR.

Aug; 7, 1945. A. J. HOLMAN Y SPHERICAL SURFACE GENERATING DEVICE Filed Nov 14, 1942 8 Sheets-Sheet 3 INVENTOR.

us- 1945- A. J. HOLMAN SPHERICAL SURFACE GENERATING DEVICE Filed Nov. 14, 1942 8 Sheets-Sheet 4 I N VENTOR.

I Aug. 7, HOLMAN 0 SPHERICAL SURFACE GENERATING DEVICE Filed Nov. 14, 1942 8 Sheets-Shet 5 INVENTOR.

7, 1945- A. J. HOLMAN SPHER ICAL SURFACE GEN ERATING DEVICE Filed Nov. 14, 8 Sheets-Sheet 6 I N VENTOR.

Aug. 7, 1945- A. J. HOLMAN SPHERICAL SURFACE GENERATING DEVICE n 8 Sheets-Sheet 7 Filed Nov. 14, 1942 INVENTOR.

1945- A. J. HOLMAN 2,381,449

SPHERICAL SURFACE GENERATING DEVICE Filed Nov. 14, 1942 Ls Sheets-Sheet 8 INVENTOR.

Hl HIHIIH-HHHH Patented Aug. 7, 1 945 UNITE 5 s PATENT OFFICE SPI IERICAL SURF::; :;;ERATH\IG DEVICE I Arum J. Holman, Brighton, N. Y. Application November 14, 1942, Serial No. 465,605

' 23 Claims.

My invention relates to apparatus for generating optical surfaces, and it has been thespecial object of my invention to make-an improved spherical grinding and polishing machine which will possess the essential characteristics of a spherical generator inherent in my former device described in Letters Patent of the-United States No. 1,827,748 dated October 20, 1931, and in addition thereto, will have the following advantages: less expensive to construct, easier to operate, better suited for mass production of lenses when operated in batteries, and adaptable for greater range of-- surface curvatures, particularly in the short radius curves. While retaining substantially all of the spherical surface generating characteristics of my rotating concentric universal joint mechanism, the present device employs moreover, the entire work spindle with the'work,

mounted thereon may be removed and transferred from machine to machine for, progressive Fig. 9 is a section through the main gear box on line !,-9 of Fig. 8.

Fig. 10 is a section through tilting bracket 9, as 'in Fig. 7, showing displacement of axes of oscillation.

Referring now more specifically to the drawings in which like reference numerals indicate like parts, I is a base of cast metal (Fig. 1) to grinding and for polishing without 'theleast danger of disturbing the precise adjustmenteither .of the radius of curvatureor of the center of oscillation, both of ,which are supercritical in all lens surface generating apparatus. This apparatus requires less skill and judgment, on the part of the v operator, than my former device 7 and it will produce more precision surfaces per hour of operation, particularly when the machines are operated in batteries and the work is Fig. 4 is a vertical section through the axis of hinge pins 7 and 8 on line L4 of Fig. 2, to somevwhat larger scale Fig. 5 is a vertical section through the tilting gear boxes on line 55 of Fig. 2

Fig. 6 is a vertical section through the'tilting gear boxes on line 6-6 of Fi 5 Fig. '7 is a vertical section through cage member 68 on line 1-1 of Fig. 3

Fig. 8 is a section through I the main gear box on line 8--8 of Fig. 3-

which are bolted supporting brackets 2 and 3, these being accurately spaced and squared at their rear ends by cross member 4. These parts, accurately fitted together and dowel ed, constitute the structural frame work of my device, serving to support the oscillating mechanisms, their driving cranks and associated gear trains.

Supporting brackets 2 and 3 (Fig. 4) have press fitted within bores at their upper extremities bearing metal bushings 5 and 6 respectively, into which are fitted with very slight clearance the hinge pins 1 and 8. The tilting bracket 9 is provided with a bore in each end, which bores are in exact alignment and into these are press fitted the pins 1 and 8. Between tilting bracket 9 and the upper end of supporting bracket 2 is hingedly mounted cage supporting member ID in the following manner: Into a bore in the upper end of cage supporting member I 0 is lightly press fitted theouter race of ball bearing H, the inner race of. which is lightly press fitted on hinge pin 1: an accurately turned projecting boss on tilting bracket 9 fits with slight clearance in the bore in cage supporting member Ill and, on the opposite side of member ID, a bore of reduced diameterflts with slight clearance over a turned projectio'non bearing metal bushing 5. By means of a spacer washer [2 ground to uniform thickness, a threaded portion [3 on hinge pin I and a threaded collar H fitting thereon, it is a simple matter to eliminate all lost motion between supporting bracket 2, cage supporting member ID and the tilting bracket 9. Hinge pin 1 is providedwith head l5 to prevent its being withdrawn from tilting bracket 9 when collar I4 is tightened securely. Collar H is provided with a set screw Hi to fix its position on hinge pin 1 after all lost motion between the parts has been eliminated. It will be apparent that this construction permits preloading of ball bearing H- and hence eliminates all end play in this bearing. In exactly the same manner, cage supporting member I! containing ball bearing l8 within a bore in its upper end, is retained on hinge pin 8 and in proper relation with tilting bracket 9 and supporting bracket 3 by the threaded collar l9 which is fixed on hinge pin 8 by set screw 20.

This construction permits cage supporting brackets l9 and I1 to swing on hinge pins I and 8 reswing on its supporting brackets 2 and 3.

Tilting bracket 9 has an integral boss 2| (Figs. 3 and 5) into a bore in which is press fitted supporting pin 22. This bore in boss 2| and the bore in tilting bracket 9 wherein hinge pin 8 is press fitted, are so arranged that supporting pin 22 and hinge pin 8 are exactly parallel as they project from tilting bracket 9. Hinge pin 8, after passing through threaded collar |9, projects through the end wall 23 (Figs. 4 and 5) of gear box 24, wherein it is a light press fit. End portion 25 of hinge pin 8 is of reduced diameter and serves as supporting stud for gears as will be explained hereinafter more fully. On the outboard end of end portion 25 is mounted a collar 26 (Fig. 4)

which is pinned to end portion 25 for the purpose hereinafter explained.

A gear box 21 (Figs. 3, 5,'and 6) has an integral boss 29 which is bored to a light press fit on supporting pin 22. The lower part 29 of gear box 21 contains a bore of somewhat larger diameter which is concentric with the bore in boss 29. Gear box 21, its integral lower portion 29, and gear box 24 are joined together (Fig. 6) by integral web 39 and by the gear box 3|. In fact, all these parts are integral portions of one and the same casting which carries; projecting from its lower portion, the radius arm 32 ending in the boss 33 (Figs. 4, 5, and 6). It will be apparent from the drawings that these integral gear boxes 24, 21, and 3| are supported rigidly from tilting bracket 9 by means of hinge pin 8 and supporting pin 22 and, furthermore, the angular position of tilting bracket 9, with respect to its supporting brackets 2 and 3, is determined by the position of radius arm 32. Any displacement of radius arm 32 from the vertical position will cause tilting bracket 9 and the rigidly attached gear box casting to swing around the axis of h'inge pins I and 8. Fitted upon the end of gear box 24, with freedom to turn thereon (Fig. 4) is gear box 34 which is held in operating position by the collar 26 previously described.

Projecting through the'bore in boss 33 at the lower end of radius arm 32 (Fig. 4) is sleeve 35 h'aving the head portion 36 contacting one face of boss 33. From the other face of boss 33 projects threaded portion 31 of sleeve 35 whereon is screwed the hollow hand grip 38. Within the sleeve 35 is slidably fitted with slight clearance the stop pin 39 Having a portion 49 of reduced diameter which passes with light clearance through a, bore in the outer end of hand grip 38 Fixed on the protruding end of portion 49 of stop pin 39 is the release grip 4| (Figs. 5 and 6). A coilspring 42 surrounding portion 49 of stop pin 39 tends to push stop pin 39 into a bore in boss 43 integral with supporting bracket 3, thereby locking tilting bracket 9 in a horizontal position with respect to is supporting brackets 2 and 3. Supporting bracket 3 also carries integral boss 44 (Fig. 2) wherein is located a bore like the bore in boss 43 and the same radial distance from hinge pin 9. Whenever it is desired to lock tilting bracket 9 in non-operating position for inspection or removal of the work, as is described fully hereinafter, stop pin 39 entering the bore in boss 44 serves this purpose.

Tilting bracket 9 supports the upp r oscillating member 49 in the following manner: A pair of diametrically opposite bosses 45 and 46 (Figs. 3 and 7) on tilting bracket 9 are bored in exact spectively, and also permits tilting bracket 9 to alignment, the axis of these bores intersecting at right angles the axis of the bores into which hinge pins 1 and 8 are press fitted. The exterior face of each boss 45 and 46 (Fi 7) is finished square to the bore, and the dimension measured from the axis of hinge pins 1 and 6 to each of these faces is identical. Within the bore in boss 45 is lightly press fitted the outer race 01' ball bearing 41, the inner race of which is a light press fit on the hinge pin 48, the latter being a good press fit in a bore in upper oscillating member 49. Within the bore in boss 46 is lightly press fitted the outer race of ball bearing 59, the inner race of which is a light press fit on the hinge pin 5 I, the latter bein a good press fit in a bore in upper oscillating member 49. The hinge pins 48 and 5| are in exact alignment and the faces of the bosses on upper oscillating member 49 from which the hinge pins protrude are finished square to the axis of the pins and to the exact same dimension'measured from the axis of upper oscillating member 49. The axis of hinge pins 46 and 5| intersects at right angles the axis of the principal bore in upper oscillating member 49. Spacer washers ofthe same thickness are placed between these faces and the inner races of the ball bearings 41 and 59, and bearing retainer caps 52 and 53, designed to maintain the exact centering of upper oscillating member 49 within the tilting bracket, 9, are arranged to preload th'ese bearings. Retaining caps 52 and 53 are attached to bosses 45 and 46 respectively by suitable screws.

Upper oscillating member 49 contains two aligned bores (Fig. 4), one in its lower end and the other in its upper end, and these bores determine the principal axis of this member. Into the lower bore is lightly press fitted the outer race of ball bearing 54, the inner race of which is lightly press fitted on sleeve 55. Into the upper bore is lightly press fitted the outer race of ball bearing 56, the inner race of which is lightly press fitted also on sleeve 55. Sleeve (01' hollow spindle) 55 contains a bore exactly concentric with the seats whereon the ball bearingsare fitted and it is also provided with a flanged head 51 against which the inner race of ball bearing 54 abuts. Flanged head 57 is relieved adjacent the outer race of this hearing, and its outer periphery is a free runnin fi't within the lower and larger bore in upper oscillating member 49. The upper end of oscillating member 49 is enlarged to form the gear box-58 having a cover 59 retained in position by suitable screws. Worm gear 69 is a snug sliding fit on sleece 55 and is suitably keyed thereto to prevent rotation on the sleeve. The upper end of sleeve 55 is threaded to fit a threaded sleeve 6| which passes through the gear box cover 59 with a slight clearance for turning. The construction of the upper oscillating member 49 is such that any desired amount of preloading on ball bearings 54 and 56 may be obtained by tightening or backing ofi threaded sleeve 6|. A spindle 62, fitted with just sufficient clearance to slide without binding in the bore in sleeve 55, carries on its lower end the tool 63. Spindle 62 is slotted on one side, and a spring actuated key pin 64, entering the slot, causes spindle 62 and tool 63 to rotate with sleeve 55. The lower end of the slot in spindle 62 is made of sufficient size and depth to allow the end of key pin 64 to enter spindle 62 to a depth somewhat greater than that of the keyway, thereby causing spindle 62 and the tool or Work mounted thereon to be locked automatically at the highest position of spindle 62 within the sleeve 55. A worm 65 (Fig. 7) meshes with worm gear 69 and causes sleeve 88 to rotate when shaft 88, whereon worm gearv 88 is mounted, is power actuated as described hereinafter.

The lower oscillating member 88, or cage, is supported from the cage supporting members I8 and I! in the following manner: A pair of rods 81 (Figs. 1 and 3) are press fitted in bores in integral bosses at the lower end of cage supporting member I8 and a like pair of rods 81 are fixed, in the same manner, in the lower end of cage supporting member II. The four rods 81 are parallel and they are so positioned that the axis ofeach rod 81, if extended, will be exactly the same distance from the common axis of hinge pins I and 8. A cage member 88 (Figs. 1 and 7') having four corner bosses 88 extending throughout its height, has bores within these bosses laid out exactly according to the geometrical pattern of the arrangement of the rods 81, so that cage member 88 may be variously positioned along rods 81 for adjustment of the radius of oscillation of the lower tool. At the exact center of the geometrical pattern formed by rods 81 and within the body of cage member 88, are two aligned bores, the upper bore having lightly press fitted therein the outer race of ball bearing I8 (Fig. '7), the lower bore having lightly press fitted therein the outer race of ball bearing II. A sleeve 12 is provided with concentric seats whereon the inner races of ball bearings I8 and 'II are lightly press fitted. Sleeve (orhollow spindle) I2 has a flanged head against which tool I8 seats when it is screwed into position in the threaded bore in the upper end of sleeve I2. A sealing ring I8, fixed on the flanged head of sleeve I2, serves to prevent entrance of abrading material into ball bearings 18 and II. A gear box 18, projecting downwardly from the body of case member 88, is provided with a cover plate I8 which is held in position by suitable screws. A worm gear 11, snugly slidable on leeve 12, is keyed thereto to prevent rotation on the sleeve. The lower end'of sleeve 12 is threaded to flt a threaded sleeve I8 which passes through cover plate I8 with slight clearance for turning.

Any desired amount 01' preloa'ding on ball bearings I8 and II may be had by tightening or backing oil threaded sleeve 18. A worm 18 (Fig. 1) meshes with worm gear "and causes sleeve I2 to rotate when shaft 88, whereon worm gear I8 is mounted, is power actuated as described herein-- after.

It will be understood from the description of my device thus far that, when the central bore in cage member 88 stands in a vertical position and upper oscillating member 88 is also vertical, then sleeves (or hollow spindles) 88 and I2 will be in exact alignment and a rod, exactly fitting each of these bores, may be pushed through both of these sleeves simultaneously. This is the ultimate and final test of the accuracy of construction and assembly of my device.

My mechanism, as thus far described, provides freedom for rotation of upp r (convex) tool 83 and lower (concave) tool I8: moreover, cage member "is free to oscillate about the axis of hinge pins I and 8, and upper oscillating member 88 is free to oscillate about the axis of its hinge pins 88 and 8|: the axis of rotation of each spindle intersects, at right angles, the axis whereon it oscillates: the axes of oscillation lie in a common plane and intersect at right angles. The mechanism for controllin and actuating the rotative and oscillatory movements of these parts will now be described.

Attached to the upper finished surface of cross member 8 at the right side of the machine by screws 8I (Fig. 3) is bearing bracket 82 which serves a dual function; first, it journals the crank shaft for oscillating the cage; second, it supports the main gear box. Bearing bracket 82 has an integral end flange 88 (Fig. 9) from the finished face of which projects annular boss 88 having a finished-bore wherein is press fitted flanged bearing bushing 88. The outside surface of annular boss 88 is turned concentric with bearing 85. Gear box 88 contains a bore which fits with slight clearance over annular boss 88 and seats on a finished surface against end flange 88 on hearing bracket 82 and is held in position thereon by three screws 81 (Figs. 8 and 9) and by two through dowel screws 88. Crank shaft 88 is journaled, near one end, in flanged bearing bushing 88 and has press fitted on this end spur gear 80 which is suitably keyed and retained in position by nut 8|. Meshing with spur gear 88 is gear 82 which, in turn, meshes with gear 88 fixed on main drive shaft 88, the latter being journaled in a flanged bearing bushing pressed in gear box cover I28 and in a flanged bearing bushing pressed in a bore in the back of gear box 88. Gear 82, serving as an idler between gears 88 and 83, rotates on stud 88 which is fixed in the free end of arm 88, the latter being mounted-so that it may swing around the axis of main drive shaft 88. A clearance bore 81 in gear box 88, through which stud 88 passes is large enough to permit meshing of the driving gears if a gear somewhat larger or smaller in diameter than gear 88 is used to vary the cyclic pattern of the abrading movements as is hereinafter fully explained. A hardened steel washer 88 and a nut 88 serve to lock stud 85 in position after proper meshing relation has been established between gears '88 and 82. Main drive shaft 88 has fixed on its outboard end the pulley I88 and its other end I8I, projecting through the rear wall of gear box 88 (Fig. 1), serves as a connection to drive, throughflexible shaft I82, the worm shaft 88 (Fig. 7) for the purpose of rotating convex' tool 88.

Power to rotate concave tool 18 is applied in the following manner: A'helical gear I88 (Figs. 8 and 9), press fitted on and'keyed to main drive shaft 88 meshes with helical gear I88, of somewhat smaller diameter, which is press fitted on shaft I 88, the latter being journaled at one end in a bearing bushing I88 press fitted in gear box 88 and at the other end in a bearing bushing fitted into bearing plate I81 which is retained in position on gear box 88 by screws I88. The end of shaft I88, projecting through bearing plate I81 (Figs. 2 and 8), serves as a connection to drive, through flexible shaft I88, the worm shaft 88 (Fig. 1) for the purpose of rotating concave tool 18. To provide convenient means whereby the rotation of concave tool I8 may be reversed with respect to the rotation of convex tool 88, I have installed a second shaft II 8, identical with shaft I88 and journaled in like manner, and having press fitted thereon helical gear III like helical gear I88 in all respects, except of opposite hand;

advantage when inspecting the work, prior to re-" move] from the machine, after tilting bracket 3 has been rocked up into non-operating position. Power to oscillate cage member 58 and the work or tool carried thereon is applied in the following manner: Crank shaft 8 9, journaled at one end in bearing 85 (Fig. 9) as hereinbefore described, is

journaled near its other end in flanged bearing bushing II2 (Fig. 3) which is press fitted in the opposite end of bearing bracket 32. This end of crank shaft 59 carries securely fixed thereon crank disc H3 whichis V-grooved on one side to fit against a beveled side of crank pin supporting block H4 and is square notched directly opposite to abut against the square side of clamping plate I I5, the latter being beveled along its opposide side to contact the opposite beveled side of crank pin supporting block II4. Two screw H5, passing through clamping plate I I5 and threaded into crank disc H3, serves to lock crank pin supporting block II4 into such position of eccentricity with respect to crank shaft 39 as is re-- quired to give any desired crank throw from zero to the full radius of the crank disc. Crank pin II 1, fixed securely in crank pin supporting block II4, rotates freely in a bearing in the crank end of connecting rod H8. The opposite end of connecting rod III! is forked, and a bearing in each ings (not shown) pressed in opposite walls of gear end of sleeve I33, and on the opposite end thereof is press fitted helical gear I34. Pressed into each 1 end of. sleeve I33is a flanged bearing bushing I35 forked end is a. free turning fit on connecting rod screws H9 (Fig. 4) which are screwed securely, into bosses I20 and I2I integral with cage sup-..

porting members It and I1 respectively. Driving power applied to crank shaft 89, through the gear train hereinbefore described (Fig. 9) will cause cage member (ill to oscillate at whatever amplitude, within the range of adjustability, the crank pin supporting block is set to provide.

Mechanism to operateupper oscillating member 49, to be effective and convenient in operation, must permit tilting bracket 8 to be shifted into operating and non-operating position freely and without disconnecting any mechanical parts or unmeshing and remeshing any elements of the gear train. .The following means, beginning at gear 90 (Figs. 8 and 9), has been devised for performing this function: A spur gear I22. a dupli-.

cate of gear 92', rotates on stud I23 which is fixed. in the swingable end of arm I24, the latter being mounted so that it may swing around the axis of shaft I25. Shaft I25 is journaied at one end in a bearing press fitted into gear box cover I23 (Fig. 9) and at the other end in a bearing press fitted in a bore in the rear wall of gear box 85. A spur gear I21, a duplicate of gear 93, is fixed on shaft I25 and meshes with gear I22, the latter act ng as an idler between gears 80 and I21. The structures here are a duplication of the structures described hereinbefore in connection with gears 50, 92, and 83 and serve the same purpose; namely,,

to allow replacement of gear 93 by a gear somewhat larger or smaller in diameter to vary the motion pattern between the abrading members. Fixed on shaft I25 is helical gear I28 which meshes with helical gear I29 fixed on shaft I30. Shaft I30 is journaled in the upper part of main gear box 86 in bearings pressed into opposite side walls of this gear box (Fig. 8).

Shaft I30 (Figs. 2 and 3) extends from main gear box 86 into gear box 34 which is fitted uoon the end of gear box 24 (Fig. 4) as hereinbefore described. Shaft I30 is suitably journaled in bearand these bushings are reamed to a free running fit on end portion 25 of hinge pin 3. The flanges on these bushings, bearing at one end against the shoulder on hinge pin 3 and at the other end against the inner wall of gear box 34, take the end thrust from helical gears I32 and I34 which preferably, are of the same hand to minimize end thrust. In alignment with helical gear I34 in gear box 24, and meshing therewith is helical gear I35 in gear box 3I (Figs. 6 and 6). Gear I33 is a free running .fit on-stud I31 which is threaded and screwed into a tapped hole in end wall 23 of in bearing support I42, the latter having a cylindrical surface turned to a good fit in the bore in lower part 29 of gear box 21 and being held in position therein by screws passing through its flanged end and entering tapped holes in the gear box. Also fast mounted on shaft I33 is helical gear I43, identical with gear I35, and gear I43 meshes with helical gear I 44 which is, fast mounted on crank shaft I45. Crank shaft I45 is journaled at one end in bearing bushing Hit pressed into a recess in gear box cover I41, the latter being secured to gear box 21 by suitable screws. Within a bore in the rear wall of gear box 21 in alignment with bearing bushing I46, are press fitted two flanged bearing bushings (4b wherein is journaled crank shaft I45. A crank disc I43, fixed on the end of crank shaft I45 and bearing against the flange ofv one bushing I68, and gear I44,-bearing against the flange on the other bushing I43,take up the end thrust of hellcal gear I44 in either direction. Crank disc I49, identical with crank disc II3, carries the same kind oi. adjustable crank pin mechanism as hereinbefore described, and to this crank pin is at tached connecting rod I53. This connecting rod (Figs. 1, 3, and 7) is also forked at one end and each forked end is provided with a bearing which is a good turning fit on connecting rod screws RBI (Fig. '7) which are screwed firmly into tapped holes in bosses located diametrically opposite each other on the upper part of upper oscillating member 49.

This mechanism for actuating upper oscillating member 49, provides complete freedom of movement of tilting bracket 3 and all mechanism attached thereto which must swing about the axis of hinge pins 1 and 8 whenever upper spindle 32 is to be removed from the machine or the work on the spindle is to be examined critically.

Basic principle 0] abrading action It will be evident, after reading the foregoing detailed description of this device, that, over the working area of the tool and over the area of the work whereon a spherical surface is being generated, the abrading action is determined by the composite motion pattern resulting from the combination of four primary movements of which the work and the tool each perform two. Mechanism has been hereinbefore described which actuates rotatively both the tool and the work in the same or in opposite directions and at slightly different rates, the exact difference in rate being determined by the relative diameters of gears I03 and IN. If both tool and work are rotating in the same direction, then the one of these which is mounted on the cage-member will rotate slightly faster than the other which is supported from the upper oscillating member. Operating with this driving arrangement the absolute difierence in rotation between the abrading elements is slight: it amounts only to the slight creep per revolution by which the cage mounted part advances ahead of the part carried by the upper oscillating member. Operating with the drives arranged to rotate tool and work in oppositedirections, the absolute difference in rotation of these parts is multiplied several times; the creep between abrading members in this case, serving primarily to break up the motion pattern.

The mechanism described provides for oscillation of the upper oscillating member and of the cage, in planes at right angles and at slightly different frequencies. The frequency difference is determined, of course, by the relative rates of rotation of the two cranks which drive the oscillating members. The gear ratios in the upper oscillating member gear train are such that shaft ill (Figs. 2 and 9) rotates exactly four times as fast ascrank disc "9. Gears I28 and I2! (Fig. 8) are the same size and, inasmuch as gearl22 is only an idler. the ratio of gears 90 and I 21, together with the four to one ratio above noted, determines the difference in rotative rate between crank discs H3 and I". In this machine, as originally designed, gear I21 has 23 teeth and gear 80 has 89 teeth. If gear 90 had 92 teeth the ratio of gear 90 to gear I21 would be 92/23 or 4 to 1, then both crank discs would rotate in synchronism and there would be no freq ency difference. By using gears of 23 teeth, and 89- teeth (both prime numbers) these gears do not return to' the exact same meshing position till the smaller gear has made 89 revolutions. During this period upper crank disc I49 has made 89/4 or 22% revolutions and crank disc I I3 has made 23 revolutions. With these gear ratios the cranks cannot possibly return to the exact same relative positions till upper crank disc 9 has made 89 revolutions. This factor multiplied by the factor relating to relative rotation of tool and work gives a very long period for the cycle of the composite motion pattern. As hereinbefore indicated, provision is made in the mechanism for substituting gears having from one to four teeth more (or less) than gear 90 and by making such substitution the motion pattern cycle may be varied over a wide range. e

Inasmuch as this machine provides for rotation of each abrading member by independent power drive and for oscillation of each abrading member in planes at right angles by independently adjustable power drives it is obvious that. with respect to the action at the abrading surfaces, this device produces substantially the same conditions as my former concentric rotatable universal joint mechanism hereinbefore referred to. This mechanism will, therefore, do substantially the same sort of spherical surface generating work as is done by my former machine.

Operation of device The first thing to be done in using my device is to mount concave and convex tools, which have been previously machined to the desired radius of curvature, in the machine. The concave tool I! (Fig. 7) is securely seated in spindle I2 and cage member 8 is elevated or lowered, as the case may require, by sliding along rods 1 until the concave surface of the tool is centered at the point of intersection of the axes of hinge pins 1 and l and hinge pins 48 and Ii. The exact position for the cage member I is determined by the use of a pin gage of the proper length centered in. and seated against the flanged head 51 of upper'sleeve l5 and bearing, at its lower end, against the surface of tool It. With the lower tool thus correctly positioned the upper oscillating member 4| (Fig. 4) is tilted back into inoperative position and upper spindle 62 with tool 63 mounted thereon is inserted in upper sleeve 55 and pushed all the way in till key pin 64 looks the spindle in place. The upper oscillating member is then rocked back into operative position; the upper end of spindle i2 projecting above the upper oscillating member is grasped by one hand; key pin 84 is withdrawn and tool 63 is seated gently against'tool 13. The throw of each crank, one o'n'crank disc H3 and the other on crank disc H9, is adjusted to make the amplitude of each oscillating member the same when the amplitudes are measured at the abrading surface of the concave tool 13. The actual amplitude is determined, of course, by the diameter of the work to be surfaced.

The machine is now ready for grinding in the tools. The upper tool 83 is elevated, abrading material is applied to the concave surface of the lowertool and the upper tool is dropped back on the lower tool. Power is applied through pulley IM to operate the machine which is allowed to run till the abrading material is'worn out. New abrading material is added as required, and

additional water may be applied by using an atomizer while the machine is in operation. More pressure between the tools may be had by loading, by weights or preferably. by spring mechanism, the upper end of spindle 82 where it projects above upper oscillating member 49. The tools are ground together with progressively finer abrading materials till, when run together after being wiped free of abrading material, each tool shows all over contact with the other; i. e., until no clouds are apparent on the surface of either tool.

To-grind convex work, the upper tool spindle is removed from the machine and a work spindle carrying the work, is inserted in its place. The procedure for roughing and fine grinding convex work is the same as previously described for grinding the tools. To grind concave work the procedure is as follows: The concave tool is left in the machine after it has been ground to exact curvature against the upper tool. The upper tool is dropped down into contact with the concave tool and a stop, slidable on the upper end of tool spindle 62, is pressed against the upper end of sleeve 6! and is locked in that position on spindle 62. This arrangement makes it possible to elevate the upper spindle to its highest position where it will be locked automatically by key pin 64, which operation will permit removal of the concave tool and insertion of a chuck whereon the work to be concave ground is mounted; The convex tool may then be released and lowered into grinding contact with the work. The upper tool will continue to grind the work, if abrading material is added, until the tool descending into the work surface can go no further because of the stop on spindle 62 having contacted the upper end of sleeve 6|. At this position the tool surface is oscillating on the exact radius at which it was ground originally against the bottom tool and hence it will generate the concave spherical surface of the correct radius on the work.

When polishing concave surfaces the upper tool spindle 62 is removed and a spindle carrying a pitch polisher mounted on its lower end is inserted in sleeve 55. The polisher, fed to the concave work by gravity or spring means, as previously mentioned in connection with tool grinding, may

be formed when warm against the concave surface of the work. After the polisher has cooled, it will generate a true concave spherical surface on the work of substantially the same radius to which the work has been fine ground.

The procedure for polishing convex surfaces has been established in connection with my former spherical generator, and mechanism substantially the same as described in my Letters Patent of the United States No, 1,82%7-48, is used with the present spherical surface generator. After fine grinding of a convex spherical surface has been completed, the stop on the top ofspindle 62 is set against the top of sleeve 6|, as previously described in connection with setting the radius of oscillation of the convex tool for grinding cona cave work surfaces. By thus establishing the radius of oscillation at which the convex Work surface has been fine ground, it is possible to raise the work spindle, remove the concave tool from lower sleeve 12 and substitute a pitch polishing tool. When the work spindle is dropped to the lowest position determined by the set stop the surface of the work will be at the exact same radius from the center of oscillation of the mechanism as it was when it was fine ground. The work spindle is then looked in this position and the pitch polisher, fed upward against the convex work surface under suitable spring tension provides suflicient pressure to rouge polishthe work surface.

As is the case with my former lens generating machines, this device, performing those motions required by the geometry of the surface, not only generates a spherical surface on the work but also continually regenerates a mating spherical surface on the tool. In other words, any two pieces of amterial, whatever their initial shape, if ground together in this machine with abrading material between them and ground together long enough, each of these pieces of material will have generated upon it by the other a true spherical surface exactly mating the other. In a true generating machine the work takes its surface form from the movements it makes with respect to the tool, rather than from the surface shape of the tool, and the surface of the tool, if initially not correct in form or not true to the axes of the machine, will be' regenerated automatically to correct form and true to the control axes of the machine.

The essential difference in the present device, compared to my former mechanism, resides in the means for rotating the work and tool. In the former mechanism both of the oscillating structures are also rotated and within each oscillating structure the work (or tool) is either fixed or was essential that they be suspended from universal joints and the rotation of the structures was accomplished through rotating these universal joints. In the present device, hollow spindles within the oscillating members are rotated through flexible shaft drives and substantially equivalent abrading conditions are obtained without requiring rotation of the oscillating structures,

This arrangement greatly simplifies the structures, renders the construction more open and get-at-abl'e so that much shorter radius curves may be handled, and permits use of one gimbal ring by means of which the upper oscillating member may be rocked out of operating position without, in the least degree, disturbing the accuracy of centering or the radius of oscillation of either the work or the tool. This latter feature of the present device is most important because; firsti it permits critical inspection of the work at all stages of grinding and during polishing without requiring removal of the work from the machine; and second, it allows transfer of the work and spindle whereon the work ismounted from machine to machine for progressive grinding and for polishing. This facility makes it practical and economical to arrange machines in groups or batteries, each individual machine being equipped with tools and operating with abrading material for a particular grain of grinding from the coarsest roughing to the finest fine grind, also with polishing tools, pitch coated, and operating with rouge for the finest known polishing. The work, mounted on a spindle, is transferred from machine to machine by simply transferring the spindle after the operation in one machine is completed. This arrangement saves the time required to change over and clean up the machine between operations when all grades of grinding and the polishing operation are carried out on one machine. It also practically eliminates the danger of contaminating the work with a coarser grade of abrading material when changing to progressively finer abrading, thereby avoiding one of the major sources of scratches, an ever present danger in lens manufacture. In operating the present device in batteries, each machine does only one grade of .abrading and only the work, as it advances from machine to machine, requires thorough and careful washing and cleaning to avoid scratches on the finished surface.

The mechanism, as hereinbefore described, is set up to produce true spherical surfaces; i. e., all movements, both rotative and oscillatory, take place around the center of curvature of the abrading surface generated upon the tool by the operation of the machine. In other words, the setup thus far described conforms to the geometry of a spherical surface. Certain types of high grade photographic lenses can be improved in performance characteristics if a surface on one or more elements is made very slightly aspheric. This fact has been known and'generally recognized by optical designers for years but there has been no satisfactory means available for producing such surfaces, even in limited quantities. With my present device there are several ways of generating aspheric surfaces which may be duplicated exactly in any desired quantity. Duplication of aspheric surfaces is possible because the mechanism will, of, itself, ultimately produce that stabilized harm of aspheric surface on the toolsfor which it is adjusted regardless of the initial surface contour of'the tools when put on e the machine.

Considered geometrically, there are two ways of .decentering my mechanism, any one or both of which would produce aspheric surfaces; first, vertical displacement of one axis of oscillation; second, lateral displacement of either or both oscillating members'with respect to the common vertical axis of the spindles. Each combination of the various possible decentrations will produce 'a different aspheric surface pattern but in all cases each surface will be symmetrical about its principal axis; i. e., it will be a surface of revolution. Mechanically, the decentration may be brought about by substituting in the mechanism other tilting brackets 9 wherein the hinge pin axes lie in slightly spaced parallel planes, and/or wherein one of the axes of oscillation is not positioned symmetrically with respect to the centering faces of the bosses wherein the other pair of hinge pins are supported. This deliberate misalignment and decentering of the axes of oscillation is illustrated in Fig. wherein the aligned bores on axis A-A are equivalent to the bores wherein ball bearings 41 and 50 are mounted as shown in Fig. 7. In Fig. 10, the vertical axis B-B is drawn midway between the faces of bosses 45 and ii. The bore 1, wherein hinge pin 1 is press fitted, is disposed at right angles to axis:AA: it is centered on axis B--B but is offset vertically fromaxis AA by an amount a. The hinge pin bore 1', shown in broken line, on

the other hand, is "centeredon axis 'A-A but offset radially from axis 3-3 by an amount b.

' Hinge pin bore 1", shown in broken line, combines vertical oiiset c and radial offset d. The

" offsets a, he and d shown in Fig. 10 are greatly magnified so the principle may be illustrated in the drawings. In practical cases, these offsets would. not ordinarily exceed a fewv thousandths r of an inch. Lateral-decentration'in this device may also be produced by inserting various spacer washers to offset an oscillating member.

While I have described particular structures for performing the various movements required I of a spherical surface generating mechanism, which structures also provide certain-new facilities and utilities not possessed by' my former device, it is recognized that other usable structures capable of performing the same functions may occur to those skilled in the art, particularly after observing the performance of my present mechanism; The claims forming a part of this application and hereunto attached are drawn with suilicient scope tolcover any and all mechof the character described which possess the mechanicalfreedom of movement and adjustability to perforni'fully thefunctions which my-device intended-toperform.

- Havingthus laim is:

- name structure; upper oscillating member fully described my-de'vice, what I hingedly supportedfon said frame structure, a

sleeve rotatably supported within said upper oscillating member, 'a work spindle slidable within said sleeve but keyed to rotate therewith, a'cage member hingedly supported on said frame structure, a second sleeve rotatably supported within said cage member, a tool mounted on said second sleeve, and means adapted and arranged to oscillate said upper oscillating member and said cage member about their respective hinge suplying in the same plane as the axis of said firstports while rotating said sleeves and the work spindle and tool carried thereby.

2. A spherical surface generating device comprising a frame structure, an upper oscillating member hingedly supported on said irame structure, a sleeve rotatably supported within said upper oscillating member, a tool spindle slidable' within said sleeve but keyed to rotate therewith, a cage member hingedly supported on said frame structure, a second sleeve rotatably supported within said cage member, a work supporting chuck mounted onsaid second sleeve, and means ported in said frame structure, the axis of said second pair of hinge pins lying in the same plane as the axis of said first-mentioned pair of hinge pins and intersecting the same at right angles, a

cage member carried on said second pair of hinge pins, a second sleeve rotatably supported within said cage member, the axis of said second sleeve intersecting the axis of said second pair of hinge pinsat right angles, a tool carried on said second sleeve, means for oscillating simultaneously the hinge. pin supported members, and means for rotating said'sleeves.

4. A spherical surface generating device comprising aframe structure, a pair of aligned hinge pins supported in the upper portion of said frame structure, an upper oscillating member carried on said hinge pins, a sleeve rotatably supported within said oscillating member, work supporting means controlled by said sleeve, a second pair of alignedhinge pins supported in said frame structure, the axis of said second pair of hinge pins mentioned pair of hinge pins and intersecting the sameat right-angles, a cage member carried on (said second pair of hinge pins, a second sleeve rotatably supported within said cage member, a tool carried on said second sleeve, the axis of each of said sleeves standing at right angles to the axis of its respective hinge pins at the point where the hinge pin axes intersect at right angles, means for oscillating simultaneously the hinge pin supported members, and means for rotating said sleeves.

5. I In a surface generating device, a frame structure, a pair of aligned hinge pins supported 'in the upper portion of said frame structure, an

upper oscillating member carried on said hinge pins, a sleeve rotatably supported within said oscillating member, a second pair of aligned hinge pins supported in said frame structure, the axis of said second pair of hinge pins lying in the same plane as the axis of said first-mentioned pair of hinge pins and intersecting th'fsame at right angles, a cage member carried on said second pair of hinge pins, a second sleeve rotatably supported within said cage member, the axis of each of said sleeves standing at right angles to the axis of its respective hinge pins and displaced somewhat from the point where the hinge pin axes intersect at right angles, mean for oscillating the hinge pin supported members, and means for rotating said sleeve.

6. A surface generating device comprising a frame structure, a pair of aligned hinge pinssupported in the upper portion of said frame structure, an upper oscillating member carried on said hinge pins, a sleeve rotatably supported within said oscillating member, work supporting means controlled by said sleeve, a second pair of aligned hinge pins supported in said frame structure, the axis of said second pair of hinge pins being disposed at right angles to the axis of said firstmentioned pair of hinge pins, a cage member carried on said second pair of hinge pins, 9. second sleeve rotatably supported within said cage member, a tool carried on said second sleeve, the axis of each of said sleeves standing at right angles to the axis of its respective hinge pins,

means for oscillating the hinge pin supported members, and meansfor rotating said sleeves.

7. In a surface generating device, a frame structure, a pair of aligned hinge pins supported in the upper portion of said framestructure, an upper oscillating member carried on said hinge pins, a sleeve rotatably supported within said oscillating member, a second pair of aligned hinge pins supported in said frame structure, the axes of said first-mentioned pair and said second palrof hinge pins lying in different planes, a cage member carried on said second pair of hinge pins, 9. second sleeve rotatably supported within said cage member, the axis of each of said sleeves standing at right angles to the axis of its respective hinge pins, means for oscillating the hinge pin supported members, and means for rotating said sleeves.

, 8. A surface generating device comprising a supporting frame structure, a pair of aligned hinge pins mounted in the upper portion of said frame structure, a tilting bracket containing end bores wherein said hinge pins are press fitted and aligned cross bores positioned symmetrically at right angles to the axis of said end bores, a second pair of hinge pins mounted in said cross bores, an upper oscillating member carried on said second pair of hinge pins, a sleeve rotatably mounted within said upper oscillating member, work supporting means controlled by said sleeve, cage supporting members hingedly mounted on said firstmentioned pair of hinge pins between said tilting bracket and said frame structure, a cage member carriedfrom said cage supporting members, a second sleeve rotatably mounted within said cage member, a tool' carried on said second sleeve, means attached to said tilting bracket adapted and arranged to swing said tilting bracket on said first-mentioned pair of hinge pins and lock same either in operating or work inspection position, means for rotating said sleeves, and means for oscillating simultaneously said upper oscillating member and said cage members.

9. A spherical surface generating device comprising a supporting frame structure, a pair of aligned hinge pins mounted in the upper portion of said frame structure, a tilting bracket containin end bores wherein said hinge pins are press fitted and aligned cross bores positioned symmetrically at right angles to the axis of said end bores, the axes of said cross bores and the axes of said end bores lying in a common Plane, a second pair of hinge pins mounted in said cross bores, an upper oscillating member carried on said second pair of hinge pins, a sleeve rotatably mounted within said upper oscillating member. work supporting means controlled by said sleeve, cage supporting members hingedly mounted. on said first-mentioned pair of hinge pins between said tilting bracket and said frame structure, a cage'member carried adjustably from said cage supporting members, a second sleeve rotatably mounted within said cage member, a tool carried on said second sleeve, said upper oscillating'member and said cage member being so organized and positioned within said supporting frame structure that the axis of said first-mentioned sleeve and the axis of said second sleeve are in exact alignment when said sleeves stand vertically, means attached to said tilting bracket adapted and arranged to swing said tilting bracket on said first-mentioned pair of hinge pins and lock same either in operating or work, inspection position, means for rotating said sleeves, and means for oscillating simultaneously said upper oscillating member and said cage member.

10. In a device of the character specified, a supporting frame structure, a tilting bracket hingedly supported in the upper portion of said frame structure, an upper oscillatin member hingedly supported in said tilting bracket at right angles to the hinge support of said tilting bracket, 2. gear box structure attached to said tilting bracket, a crank shaft journaled in said gear box structure, adjustable crank mechanism fixed on said crank shaft, 9. connecting rod joining said crank mechanism to said upper oscillating member, a gear train within said gear box structure, and means associated with said gear box structure adapted and arranged to swing said tilting bracket and connected mechanism and lock same either in a vertical or oblique position, said gear train being adapted and arranged to oscillate said upper oscillating member and also to allow freedom for swinging said tilting bracket.

11. In a device of the character specified, a supporting frame structure, a pair of aligned hinge pins rotatably mounted in said frame structure, a tilting bracket wherein said hinge pins are press fitted, an upper oscillating member hingedly supported in said tilting bracket, a cage member swingably supported on said hinge pins, means adapted and arranged to swing said tilt ing bracket and lock same either in operating or work inspecting position, adjustable crank mech- 'anisms and enclosed gear trains carried on said supporting structure adapted and arranged to oscillate said upper oscillating member and said cage member in planes at right angles at different frequencies.

12. In a device of the character specified, a supporting frame structure, a tilting bracket hingedly supported on said frame structure, an upper oscillating member hingedly supported in said tilting bracket, a sleeve rotatably mounted within said upper oscillating member, a cage member hingedly supported in said frame structure, a second sleeve rotatably mounted within said cage member, means adapted and arranged to swing said tilting bracket and lock same in a vertical or oblique position, adjustable right angle drive crank mechanisms and their enclosed operating gear trains carried on said supporting frame structure and adapted and arranged to oscillate said upper oscillating member and said cage member in planes at right angles at different frequencies, and means for rotating said sleeves.

13. In a device of'the character specified, a supporting frame structure, a. cage member, and a tilting bracket hingedly supported in said frame structure on common hing pins, an upper oscillating member hingedly supported in said tilting bracket, a sleeve rotatably mounted in said upper oscillating member, a work spindle slidable with- 2,as1,44o 9 in said sleeve, 9. tool mounted on said cage member, and means associated with said tilting bracket adapted and arranged to swing said tilting bracket and lock same in two positions; .the first position allowing operative engagement of work carried on said work spindle with said tool mounted on said cage member, the second position disengaging said work from said tool and permitting withdrawal of said work spindle from said upper oscillating member. 14. In a spherical surface generating device, a pair of hollowspindles rotatably mounted, a work spindle slidably mounted within one of said oscillating work carrying member, the axes of said v hinge pins, an oscillating tool carrying member hollow spindles, a tool fixed on one endoi' the other of said hollow spindles, hingedly mounted means whereby said hollow spindles are supported so they may be oscillated in planes at right angles, a supporting frame structure for said hingedly mounted means, means adapted and arranged to oscillate said hollow spindles at different frequencies, and means for rotating said hollow spindles at different rates.

15. In a spherical surface generating device, a pair of sleeves rotatably mounted, hingedly mountedmeans whereby said sleeves are supported so they may be oscillated in planes at right angles, a supporting frame structure for said hingedly mounted means, means whereby one of said sleeves may be tilted in the plane of oscillation of the other of said sleeves, gear driven crank means for oscillating said sleeves adapted and arranged to allow tilting of one sleeve in the v plane of oscillation of the other, and means for rotating said sleeves while they are being oscillated,

16. In a spherical surface generating device, a

pair of hollow spindles rotatably mounted, a work spindle slidably mounted within one of said hollow spindles, a tool fixed on one end of the other of said hollow spindles, hingedly mounted means whereby said hollow spindles are supported so they may be oscillated in different planes, 8. supporting frame structure for said hingedly mounted means, means adapted and arranged to oscillate said hollow spindles at difl'erent relative irequencies, means for changing the relative frequencies by smalluincrements, and means for rotating said hollow-spindles at different rates and in the same and in opposite directions.

17. In a device for generating spherical surfaces, a supporting frame structure, a pair of aligned hingepins mounted with freedom to turn in said frame structure, a cage member supported swingably upon said hinge'pins, a tilting bracket wherein said hinge pins are press fitted, an upper oscillating member hingedly supported within said tilting bracket and adapted and arranged to swing at right angles to said cage member, said tilting bracket being made swingable about the axis of said pair of aligned hinge pins so that said upper oscillating member may be tipped out of alignment with said cage member sumciently to permit withdrawal of work for inspection and for finer grinding (or polishing) in a similar mechanism.

18. In adevice for generating true spherical surfaces, a tilting bracket, a pair of aligned bores in said tilting bracket wherein a pair of-hinge pins are pressfltted, means including a base and upright brackets for hingedly supporting said hinge pins, an oscillating tool carrying member supported on said hinge pins, a second pair of aligned bores in said tilting bracket, and means supported in said second pair of aligned bores adapted and arranged to support hingedly an supported on said hinge pins, a second pair of aligned bores in said tilting bracket, and means supported in said second pair of aligned bores adapted and arranged to support hingedly an oscillating work carrying member, the axes of said pairs ofv aligned bores being disposed at right angles to each other and lying in spaced parallel planes, the spacing'between said parallel planes having a specified, not an accidental value, for the purpose oi determining the precise nature and the exact degree of departure of the generated v aspheric surface from a true sphere.

20. In a device for generating true spherical surfaces, a tilting bracket, a pair of aligned bores in said tilting bracket wherein a pair of hinge pins are press fitted, means including a base and upright brackets for hingedly supporting said hinge pins, an oscillating member supported on said hinge pins, a hollow spindle rotatably mounted within said oscillating member, a work spindle slidably-supported within said hollow spindle, a second pair of aligned bores in said tilting bracket, a second oscillating member, means supported in said second pair of aligned bores adapted and arranged to support hingedly said second oscillating member, a second hollow spindle rotatably mounted within said second oscillating member, and a tool fixed on one end of said second hollow spindle, said pairs of aligned bores, oscillating members and hollow spindles being so organized that the axes'oi' said'aligned bores intersect at right angles and the axes of said hollow spindles pass through this intersection.

21. In a device for generating specified aspheric surfaces, a tilting bracket, a pair of aligned, bores in said tilting bracket wherein a pair of hinge pins are press fitted, means including a base and up- J right brackets for hingedly supporting said hinge pins, an oscillating member supported on said hinge pins, a hollow spindle rotatably mounted within said oscillating member, a work spindle slidably supported within said hollow spindle, a

second pair of aligned bores in said tilting bracket,

precise nature and the exact degree of departure of the generated aspheric surface from a true sphere. I

22. In a device for generating specified aspheric surfaces, 8, tilting bracket, a pair of aligned bores in said tilting bracket-wherein a pair of hinge pins are press fitted, means including a base and upright brackets for hingedly supporting said hinge pins, an oscillating member supported on said hinge pins, a hollow spindle rotatably mounted within said oscillating member, a work spindle slidably supported within said hollow spindle, a

second pair of aligned bores in said tilting bracket,

a.sec0nd oscillating member, means supported in said second pair of aligned bores adapted and arranged to support hingedly said second oscillating member, a second hollow spindle rotatably mounted within said second oscillating member, and a tool fixed at one end of said second hollow spindle, said pairs of aligned bores, oscillating members and hollow spindles being so organized that the axes of said aligned bores intersect at right angles and the axis of each of said hollow' pins, an oscillating member supported on said hinge pins, a hollow spindle rotatably mounted within said oscillating member, a work spindle slidably mounted within said hollow spindle, a second pair of aligned bores in said tilting bracket, a second oscillating member, means supported in said second pair of alignedbores adap d and arranged to support hingedly said secon oscillating member, a second hollow spindle ro tably mounted within said second oscillating m mber, and a tool fixed on one end of said second hollow spindle, said pairs of aligned bores, oscillating members and hollow spindles being so organized that the axes oi said aligned bores are disposed at right angles to each other but lie in spaced parallel planes and the axis of each of said hollow spindles-passes with specified clearance the respective axis whereon its oscillating member is hingedl supported, 

